Hasil untuk "Environmental Science"

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S2 Open Access 2020
Challenges of unculturable bacteria: environmental perspectives

A. Bodor, N. Bounedjoum, G. Vincze et al.

Environmental biotechnology offers several promising techniques for the rehabilitation of polluted environments. The modern industrialized world presents novel challenges to the environmental sciences, requiring a constant development and deepening of knowledge to enable the characterization of novel pollutants and a better understanding of the bioremediation strategies as well as their limiting factors. The success of bioremediation depends heavily on the survival and activities of indigenous microbial communities and their interaction with introduced microorganisms. The majority of natural microbiomes remain uncultivated; therefore, further investigations focusing on their intrinsic functions in ecosystems are needed. In this review, we aimed to provide (a) a comprehensive overview of the presence of viable but nonculturable bacteria and yet-to-be-cultivated cells in nature and their diverse awakening strategies in response to, among other factors, signalling extracellular metabolites (autoinducers, resuscitation promoting factors, and siderophores); (b) an outline of the trends in isolating unculturable bacteria; and (c) the potential applications of these hidden players in rehabilitation processes.

260 sitasi en
DOAJ Open Access 2026
Insights From Managed Retreat Projects in Europe

C. Wolff, F. Bade, C. M. Kraan

Abstract Managed retreat, the purposeful relocation of households and assets to reduce flood risk, is gaining recognition as an essential adaptation strategy under intensifying climate change. Although often contested and perceived as socially or politically unacceptable, managed retreat holds potential to enhance the long‐term resilience of at‐risk communities. In Europe, however, it remains comparatively underexplored, with only a handful of European managed retreat cases that have been reported on in the academic literature. Here, we present a data set of European managed retreat cases, based on a multilingual review of academic and gray literature, as well as media articles. We found 44 implemented or planned cases of managed retreat across the continent, spanning 11 countries, ranging from the relocation of individual assets to more than 1,500 households. Through a cross‐case analysis, we identify five key factors that influence the process and outcomes of managed retreat projects: the compensation offered, the timing of the project, the engagement of the affected community, the leadership taken by the government, and the post‐relocation land use. Our analysis demonstrates that, although managed retreat remains less common than engineered protection measures, it is more prevalent in Europe than previously assumed and is already being practiced in varied forms. By uncovering common challenges and enabling conditions, this study offers transferable insights for advancing more anticipatory and strategically designed managed retreat initiatives, both within Europe and beyond.

Environmental sciences, Ecology
DOAJ Open Access 2025
Soil salinity dynamics and optimal groundwater depth for salt control in farmland under surface irrigation and subsurface drainage

ZHANG Zhixiang, LIU Songtao, LI Qian et al.

【Background】Soil salinization is a widespread abiotic stress that significantly impacts agricultural productivity and water resource management in the Yinbei region of Ningxia Province. This study explores the inter-annual dynamics of soil salinity and groundwater depth in areas within this region that use surface irrigation and subsurface drainage.【Method】Field investigations were conducted in Huinong, a representative area in northern Yinbei characterized by surface irrigation and subsurface drainage systems. Spatiotemporal variation of soil salinity and groundwater depth were analyzed using measured data with the help of correlation analysis and the inverse distance weighting (IDW) interpolation method.【Result】Temporally, areas with high soil salinity were accounting ting for 23.57% of the study region in April. In contrast, areas with soil salinity greater than 2 g/kg decreased by 52.99% in July and 26.3% in October, compared to April. Soil salinity decreased gradually with increasing groundwater depth, and the relationship between them was well fitted by a proposed model (R2> 0.82).【Conclusion】Soil salinity in the region peaks in spring and declines by summer, showing spatial variability influenced primarily by topography and irrigation practices. Salinity in the 40-100 cm soil layer was more responsive to groundwater depth than in the 0-40 cm layer. Maintaining a groundwater depth between 1.8 and 2.2 m can facilitate crop growth and reduce salinization risk.

Agriculture (General), Irrigation engineering. Reclamation of wasteland. Drainage
DOAJ Open Access 2025
Air pollution mapping and variability over five European cities

Karine Sartelet, Jules Kerckhoffs, Eleni Athanasopoulou et al.

Mapping urban pollution is essential for assessing population exposure and addressing associated health impacts. High urban concentrations are due to the proximity of sources such as traffic or residential heating, and to urban density with the presence of buildings that reduce street ventilation. This urban complexity makes fine-scale mapping challenging, even for regulated pollutants such as NO2 and PM2.5. In this study we apply state-of-the-art empirical and deterministic modeling approaches to produce high-resolution (<100 m) pollution maps across five European cities (Paris, Athens, Birmingham, Rotterdam, Bucharest). These methodologies enable full-city mapping capturing intra-urban gradients of concentrations. Depending on the methodology, regulated pollutants (NO2, PM2.5) and/or emerging pollutants (black carbon (BC) and ultrafine particles (UFP characterized here by particulate number concentration PNC)) are considered. For deterministic modelling, different approaches are presented: a multi-scale Eulerian modelling chain down to the street scale with chemistry/aerosol dynamics at all scales, multi-scale hybrid models with Eulerian regional dispersion and Gaussian subgrid dispersion, and a Gaussian-based model. Empirical land use regression models were developed based upon mobile monitoring.To compare the relative performance of the methodologies and to evaluate their performance and limitations, the modelling results are compared to fixed measurement stations. We introduce a standardized metric to quantify spatial and seasonal variability and assess each method’s capacity to reproduce fine-scale urban heterogeneity. We also evaluate how data assimilation affects both concentration accuracy and variability representation—particularly relevant for emerging pollutants where measurement data are sparse. We confirm established seasonal and spatial patterns: spatial variability is more pronounced for PNC, NO2 and BC than PM2.5, and concentrations are higher during the winter periods. We also observe reduced spatial variability in winter for PM2. 5 (linked to residential heating) and for BC in cities with significant wood burning emissions. This study adds unique value by evaluating these patterns using fixed measurement stations, and quantifying them across entire urban areas at very fine spatial resolution (<100 m). Furthermore, important methodological strengths and limitations are pointed out, providing practical guidance for the selection and improvement of urban exposure mapping methods, supporting the implementation of the new EU Air Quality Directive.

Environmental sciences
DOAJ Open Access 2025
Generative Lagrangian data assimilation for ocean dynamics under extreme sparsity

Niloofar Asefi, Leonard Lupin-Jimenez, Tianning Wu et al.

Reconstructing ocean dynamics from observational data is fundamentally limited by the sparse, irregular, and Lagrangian nature of spatial sampling, particularly in subsurface and remote regions. This sparsity poses significant challenges for forecasting key phenomena such as eddy shedding and rogue waves. Traditional data assimilation methods and deep learning models often struggle to recover mesoscale turbulence under such constraints. We leverage a deep learning framework that combines neural operators with denoising diffusion probabilistic models to reconstruct high-resolution ocean states from extremely sparse Lagrangian observations. By conditioning the generative model on neural operator outputs, the framework accurately captures small-scale, high-wavenumber dynamics even at 99% sparsity (for synthetic data) and 99.9% sparsity (for real satellite observations). We validate our method on benchmark systems, synthetic float observations, and real satellite data, demonstrating robust performance under severe spatial sampling limitations as compared to other deep learning baselines.

Environmental sciences, Electronic computers. Computer science
DOAJ Open Access 2025
A Systematic Review on the Toxicology of European Union-Approved Triazole Fungicides in Cell Lines and Mammalian Models

Constantina-Bianca Vulpe, Adina-Daniela Iachimov-Datcu, Andrijana Pujicic et al.

Triazole fungicides are widely used in agriculture but may pose risks to human health through occupational, accidental, or environmental exposure. This systematic review aimed to evaluate the toxicity of ten European Union-approved triazole fungicides in rodent models and cell lines. A total of 70 studies were included, reporting quantitative in vivo oral, dermal, or inhalation toxicity in mammals or quantitative in vitro cytotoxicity in human or mammalian cell lines; the exclusion criteria comprised publications not in English or not accessible. Literature searches were conducted in Web of Science, Google Scholar, and the Pesticide Properties DataBase (PPDB), and risk of bias in included studies was assessed using ToxRTool. Due to heterogeneity in study designs, reporting formats, and endpoints, data were synthesized descriptively. Quantitative endpoints included LD<sub>50</sub>/LC<sub>50</sub> values for in vivo studies and LOEC, IC<sub>50</sub>, LC<sub>50</sub>, and EC<sub>50</sub> values for in vitro studies, while mechanistic endpoints highlighted apoptosis, oxidative stress, genotoxicity, and endoplasmic reticulum stress. Difenoconazole and tebuconazole were the most extensively studied compounds, whereas several triazoles had limited data. The limitations included heterogeneity of data and incomplete reporting, which restrict cross-study comparisons. Overall, the findings provide a comprehensive overview of potential human health hazards associated with EU-approved triazole fungicides and highlight critical knowledge gaps. The review was registered in Open Science Framework.

Therapeutics. Pharmacology, Toxicology. Poisons
DOAJ Open Access 2024
Planning and construction of Xiong'an New Area (city of over 5 million people): Contributions of China's geologists and urban geology

Bo Han, Zhen Ma, Liang-jun Lin et al.

ABSTRACT: China established Xiong'an New Area in Hebei Province in 2017, which is planned to accommodate about 5 million people, aiming to relieve Beijing City of the functions non-essential to its role as China's capital and to expedite the coordinated development of the Beijing-Tianjin-Hebei region. From 2017 to 2021, the China Geological Survey (CGS) took the lead in multi-factor urban geological surveys involving space, resources, environments, and disasters according to the general requirements of “global vision, international standards, distinctive Chinese features, and future-oriented goals” in Xiong'an New Area, identifying the engineering geologic conditions and geologic environmental challenges of this area. The achievements also include a 3D engineering geological structure model for the whole area, along with “one city proper and five clusters”, insights into the ecology and the background endowment of natural resources like land, geothermal resources, groundwater, and wetland of the area before engineering construction, a comprehensive monitoring network of resources and environments in the area, and the “Transparent Xiong'an” geological information platform that is open, shared, dynamically updated, and three-dimensionally visualized. China's geologists and urban geology have played a significant role in the urban planning and construction of Xiong'an New Area, providing whole-process geological solutions for urban planning, construction, operation and management. The future urban construction of Xiong'an New Area will necessitate the theoretical and technical support of earth system science (ESS) from various aspects, and the purpose is to enhance the resilience of the new type of city and to provide support for the green, low-carbon, and sustainable development of this area.

Engineering (General). Civil engineering (General), Geology
DOAJ Open Access 2024
Unmanned Aerial Vehicle for Precision Agriculture: A Review

Francesco Toscano, Costanza Fiorentino, Nicola Capece et al.

Digital Precision Agriculture (DPA) is a comprehensive approach to agronomic management that utilizes advanced technologies, such as sensor data analysis and automation, to optimize crop productivity, enhance farm income, and minimize environmental impacts. DPA encompasses various agricultural domains, including pest control, pest management, fertilization, irrigation management, sowing, transplanting, crop health monitoring, yield forecasting, harvesting, and post-harvest stages. Among the enabling technologies for DPA, Unmanned Aerial Vehicles (UAVs) have gained significant attention and market growth. The advancements in control systems, robotics, electronics, and artificial intelligence have led to the development of sophisticated agricultural drones. UAVs offer advantages such as versatility, quick and accurate remote sensing capabilities, and high-quality imaging at affordable prices. Furthermore, the miniaturization of sensors and advancements in nanotechnology enable UAVs to perform multiple operations simultaneously without compromising flight autonomy. However, various variables, including aircraft mass, payload capacity, size, battery characteristics, flight autonomy, cost, and environmental conditions, impact the performance and applicability of UAV systems in agriculture. The economic considerations involve the purchase of drones, equipment, and the expertise of trained pilots for flight management and data processing. Payload capacity, flight range, and financial factors influence agriculture&#x2019;s choice and implementation of UAVs. The research and patent trends show the growing interest in UAVs for agricultural applications. This paper provides a general review of UAV types, construction architectures, and their diverse applications in agriculture until 2022.

Electrical engineering. Electronics. Nuclear engineering
DOAJ Open Access 2024
High P‐T Sound Velocities of Amphiboles: Implications for Low‐Velocity Anomalies in Metasomatized Upper Mantle

Wen‐Yi Zhou, Ming Hao, Dongzhou Zhang et al.

Abstract Metasomatized mantle xenoliths containing hydrous minerals, such as amphiboles, serpentine, and phlogopite, likely represent the potential mineralogical compositions of the metasomatized upper mantle, where low seismic velocities are commonly observed. This study presents the first experimentally determined single‐crystal elasticity model of an Fe‐free near Ca, Mg‐endmember amphibole tremolite at high pressure and/or temperature conditions (maximum pressure 7.3(1) GPa, maximum temperature 700 K) using Brillouin spectroscopy. We found that sound velocities of amphiboles strongly depend on the Fe content. We then calculated the sound velocities of 441 hydrous‐mineral‐bearing mantle xenoliths collected around the globe, and quantitatively evaluated the roles that amphiboles, phlogopite and serpentine played in producing the low velocity anomalies in the metasomatized upper mantle.

Geophysics. Cosmic physics
DOAJ Open Access 2024
A Generative Super‐Resolution Model for Enhancing Tropical Cyclone Wind Field Intensity and Resolution

Joseph W. Lockwood, Avantika Gori, Pierre Gentine

Abstract Extreme winds associated with tropical cyclones (TCs) can cause significant loss of life and economic damage globally, highlighting the need for accurate, high‐resolution modeling and forecasting for wind. However, due to their coarse horizontal resolution, most global climate and weather models suffer from chronic underprediction of TC wind speeds, limiting their use for impact analysis and energy modeling. In this study, we introduce a cascading deep learning framework designed to downscale high‐resolution TC wind fields given low‐resolution data. Our approach maps 85 TC events from ERA5 data (0.25° resolution) to high‐resolution (0.05° resolution) observations at 6‐hr intervals. The initial component is a debiasing neural network designed to model accurate wind speed observations using ERA5 data. The second component employs a generative super‐resolution strategy based on a conditional denoising diffusion probabilistic model (DDPM) to enhance the spatial resolution and to produce ensemble estimates. The model is able to accurately model intensity and produce realistic radial profiles and fine‐scale spatial structures of wind fields, with a percentage mean bias of −3.74% compared to the high‐resolution observations. Our downscaling framework enables the prediction of high‐resolution wind fields using widely available low‐resolution and intensity wind data, allowing for the modeling of past events and the assessment of future TC risks.

Geophysics. Cosmic physics, Information technology
DOAJ Open Access 2024
A first look into moss living tardigrades in boreal peatlands

Hennariikka Mäenpää, Merja Elo, Sara Calhim

Abstract Tardigrades (Tardigrada) are a phylum of micrometazoans found in all biomes on Earth, but their ecology and habitat preferences remain vastly understudied. Boreal peatlands include a diversity of habitat types and high structural heterogeneity that represents an interesting system to study some of the poorly known habitat preferences of tardigrades. Here, we investigate for the first time tardigrade communities in peatland mosses and the latter's potential associations with key environmental variables. We collected 116 moss samples from 13 sites representing different peatland types and management histories. We found that tardigrades are common and diverse in boreal peatlands, as tardigrades were present in 72% of the collected samples and we identified 14 tardigrade genera. Tardigrade abundance seemed to increase alongside the increasing tree basal area and the density was higher in the microtopographic level further from the water table level, that is, hummocks (mean 117/moss gram) than in lawns/hollows (mean 84/moss gram). Furthermore, the highest tardigrade density was found in the moss taxa that are associated with forested peatland types (i.e., feather mosses) (321 mean/moss gram). Finally, we found interesting patterns regarding tardigrade functional diversity, as carnivorous tardigrades were found only in peatlands with tree basal area > 20 m2 and mostly in hummocks. Our study demonstrates that the habitat heterogeneity of peatlands (e.g., variation in moisture and vegetation cover) represents an interesting system to study tardigrade ecology and habitat preferences. However, since we found variation in tardigrade abundance and communities across peatland types and microhabitats within peatlands, our results highlight that such studies should be conducted with numerous replicate samples and a systematic study design that properly addresses the habitat heterogeneity between and within different peatland types.

DOAJ Open Access 2022
Effects of maternal exercise during pregnancy on neonatal weight and subcutaneous fat thickness

Mengbi SHEN, Zixia WANG, Jiaqi ZHENG et al.

BackgroundExercise during pregnancy is closely related to maternal and infant health. Previous studies in developed countries have linked maternal exercise during pregnancy with newborn body weight as well as subcutaneous fat thickness. However, the relevant studies in China are limited, and the conclusions remain inconsistent. ObjectiveTo investigate the effects of maternal exercise during pregnancy on neonatal weight and subcutaneous fat thickness. MethodsBased on the Shanghai Birth Cohort, 959 maternal-infant pairs were included in this study. The International Physical Activity Questionnaire was used to collect average weekly frequency and daily minutes of walking in the first and second trimesters, and entropy weight method was used to calculate the cumulative exercise index in the two trimesters. Birth weight was measured using a calibrated weigh scale. Subcutaneous fat thickness was measured at abdomen, scapula, and triceps with a Harpenden skinfold caliper for all newborns and the sum of the thickness for the three sites was then calculated. A multiple linear regression model was employed to estimate the relationships of cumulative exercise index during pregnancy with neonatal body weight and subcutaneous fat thickness. Subgroup analyses stratified by pre-pregnancy body mass index (BMI) and sex of newborns were also performed. ResultsThe mean age of pregnant women was (28.5±3.8) years, and the pre-pregnancy BMI was (21.4±3.0) kg·m−2. Newborn boys were slightly more than newborn girls (54.3% vs 45.7%), and the neonatal weight was (3374.0±427.5) g. The means of newborns' abdominal, scapular, and triceps subcutaneous fat thickness were (4.4±1.3), (5.4±1.4), and (6.0±1.5) mm, respectively, and the sum of subcutaneous fat thickness was (15.8±3.9) mm. In the first and second trimesters, 77.3% and 88.7% of pregnant women walked 4 d per week and more, respectively; the daily minutes of walking was (36.9±27.2) min and (43.3±26.3) min, respectively; the cumulative exercise index was 25.6±17.7 and 35.9±21.1, respectively. The results of multiple linear regression analysis showed that the cumulative exercise index in the second trimester was negatively associated with newborns' abdominal (b=−0.006, 95%CI: −0.010-−0.003), scapular (b=−0.005, 95%CI: −0.009-−0.002), triceps (b=−0.006, 95%CI: −0.010-−0.002), and their sum of (b=−0.018, 95%CI: −0.028-−0.007) subcutaneous fat thickness (P<0.05); in the first and second trimesters, however, the relationship between maternal cumulative exercise and newborns' body weight was not significant. The results of stratified analyses showed that the negative associations between maternal cumulative exercise index and newborns' subcutaneous fat thickness for the second trimester remained significant in the subgroups of boys and neonates whose mothers had normal pre-pregnancy BMI (P<0.05). ConclusionCumulative exercise index in the second trimester is negatively correlated with the neonatal thickness of subcutaneous fat, and the association may be altered by neonatal sexes and maternal pre-pregnancy BMI levels.

Medicine (General), Toxicology. Poisons
DOAJ Open Access 2022
Hidden benefits and risks of partial protection for coral reef fisheries

Patrick F. Smallhorn-West, Philippa J. Cohen, Renato A. Morais et al.

Partially protected areas are now the dominant global form of spatial management aimed at preserving ecosystem integrity and managing human use. However, most evaluations of their efficacy use only a narrow set of conservation indicators that reflect a fraction of ways in which protection can succeed or fail. In this paper, we examine three case studies of partially protected coral reef fishery systems to evaluate benefits and risks of their use as a management tool. We use data from community-based management arrangements in three Pacific Island countries to demonstrate three vignettes of how partial protection can boost fisheries production, enhance the ease with which fishers catch their prey, and alter the composition of fisheries yields. These changes in fisheries productivity, catchability, and vulnerability under partial protection carry substantial benefits for fishers. However, they also carry significant risks for ecosystems and fisheries livelihoods unless adaptively managed so as to confer the short to medium term benefits in resource performance without risking longer term sustainability.

Biology (General), Ecology
DOAJ Open Access 2021
Influence of convectively coupled equatorial Kelvin waves on March-May precipitation over East Africa

Okello Ochieng Phillip, Tan Guirong, Ongoma Victor et al.

Convectively coupled equatorial Kelvin waves (CCEKWs) are those types of equatorially trapped disturbances that propagate eastward and are among the most common intra-seasonal oscillations in the tropics. There exists two-way feedback between the inter-tropical convergence zone (ITCZ) and these equatorially trapped disturbances. Outgoing Longwave Radiation (OLR) was utilized as a proxy for deep convection. For CCEKWs, the modes are located over the West Atlantic, equatorial West Africa, and the Indian Ocean. The influence of other circulations and climate dynamics is studied for finding other drivers of climate within East Africa. The results show a positive relationship between Indian and Atlantic Oceans Sea Surface Temperatures and March-May rainfall over equatorial East Africa over the period of 1980 to 2010. This influence is driven by the Walker circulation and anomalous moisture influx enhanced by winds. Composite analysis reveals strong lower-tropospheric westerlies during the active phase of the CCKWs activities over Equatorial East Africa. The winds are in the opposite direction with the upper-tropospheric winds, which are easterlies. Singular Value Decomposition shows a strong coupling interaction between rainfall over equatorial East Africa and CCKWs. This study concludes that Kelvin waves are not the main factors that influence rainfall during the rainy season. Previous studies show that the main influencing factors are ITCZ, El-Nino Southern Oscillation (ENSO), and tropical anticyclones that borders the African continent. However, CCKWs are a significant factor during the dry seasons.

Geography (General)
DOAJ Open Access 2020
The use of tear ferning test in cats for evaluation of ocular surface

Jéssica Fontes Veloso, Arianne Pontes Oriá, Ana Cláudia Santos Raposo et al.

Abstract Background The tear film is a trilaminar fluid composed mainly of lipids, electrolytes, proteins and water. It is responsible for lubrication, nutrition and protection against microbial and toxic agents. Disruption of any these components may weaken the ocular surface, making it more susceptible to disease. Increasing evidence suggests that qualitative tear film deficiencies are an important predisposing factor or cause of some of the most common and challenging ocular diseases in cats, including conjunctivitis, corneal ulcer, spontaneous chronic corneal epithelial defects (SCCED), pigmentary keratitis, corneal sequestrum and dry eye syndrome. The aim of this study was to describe the tear ferning test in healthy cats and to compare the results by using two grading scales for humans. Tear samples were collected using Schirmer tear test (STT) strips from 60 healthy cats, and, after centrifuging the strips to obtain the samples, the aliquot was placed on clean microscope glass until it dried and the tear ferning patterns were observed under a polarized light microscope and classified according to the Rolando and Masmali grading scales. Results Ferning patterns in the lower grades showed full crystallization with high density, without gaps between the ferns and branches, forming several nuclei that were easily distinguished. According to the Rolando scale, 50% (60/120), 46.6% (56/120) and 3.4% (4/120) of eyes showed type I, II and III patterns, respectively. According to the Masmali scale, 15% (18/120), 56.6% (68/120 eyes) and 28.4% (34/120) of eyes showed grade 0, 1 and 2 patterns, respectively. No difference was observed between the right and left eyes for both Rolando (P = 0.225) and Masmali (P = 0.683) scales. Conclusions The tear ferning test is a qualitative test that can be used in cats as a complementary evaluation of the ocular surface. While the Rolando scale showed an increased prevalence of types I and II, the Masmali scale showed an increased prevalence of grades 1 and 2. This can be attributed to the species-specific differences between human and feline tear film. So Masmali grade 2 can be considered a normal tear pattern for the species, because all the cats used in study were clinically healthy. For this reason, future complementary studies are necessary for comparing healthy eyes and eyes with different ocular surface disease in cats. Both scales can be feasible options for grading tear crystallization in cats, but as Rolando scale included 96.6% of the samples in the 2 types that are considered normal for humans, we think that this scale seemed to be more precise to classify crystallization pattern in cats. The crystallization patterns observed in this study can form the basis for standardizing ocular surface parameters in cats.

Veterinary medicine
DOAJ Open Access 2020
Influence of Variations of Hydrothermal Conditions on Normalized Difference Vegetation Index in Typical Temperature Zones Along the East Coast of China

Guangxin He, Guangxin He, Guangxin He et al.

The eastern coastal areas of China span multiple climatic zones, and the impacts of climate warming on their ecological environment show regional differences. In this research, the Normalized Difference Vegetation Index (NDVI) was used as the indicator to characterize the ecological environment, and selected Guangdong, Jiangsu, and Liaoning as its typical research areas. The authors selected the NDVI, average temperature, and precipitation data of the yearly growth season, respectively, from 1982 to 2016. This study adopted the copula functions model based on Markov Chain Monte Carlo to carry out the research of bivariate joint distribution so as to calculate the joint probability, the joint exceedance probability, the joint return period and the co-occurrence return period. The results showed that 1) the temperature and precipitation in the three regions were respectively related to the NDVI sequence showing the characteristic that was correlated at the upper tail and asymptotically independent at the lower tail, which demonstrated that the temperature and precipitation had little effect on NDVI when they reached their minimum values, and the temperature and precipitation had obvious effect on NDVI when they reached their maximum values. 2) The shorter the return period was, the wider the ranges of the climate factor and the NDVI were, showing that when the climate factor was constant, the probability of the NDVI having a shorter return period was higher. The greater the climate factor was, the longer the return period was, indicating that the probability of plant growth inhibition was higher when the climate factor exceeded a certain threshold. 3) The suitable temperature and precipitation for vegetation growth in the three regions gradually decreased from south to north. These results provide some theoretical guidance and scientific foundation for the protection of regional ecological environment and enhance the understanding of the impact of climate change on the ecosystem.

DOAJ Open Access 2019
A general theory of glacier surges

D. I. Benn, A. C. Fowler, I. Hewitt et al.

We present the first general theory of glacier surging that includes both temperate and polythermal glacier surges, based on coupled mass and enthalpy budgets. Enthalpy (in the form of thermal energy and water) is gained at the glacier bed from geothermal heating plus frictional heating (expenditure of potential energy) as a consequence of ice flow. Enthalpy losses occur by conduction and loss of meltwater from the system. Because enthalpy directly impacts flow speeds, mass and enthalpy budgets must simultaneously balance if a glacier is to maintain a steady flow. If not, glaciers undergo out-of-phase mass and enthalpy cycles, manifest as quiescent and surge phases. We illustrate the theory using a lumped element model, which parameterizes key thermodynamic and hydrological processes, including surface-to-bed drainage and distributed and channelized drainage systems. Model output exhibits many of the observed characteristics of polythermal and temperate glacier surges, including the association of surging behaviour with particular combinations of climate (precipitation, temperature), geometry (length, slope) and bed properties (hydraulic conductivity). Enthalpy balance theory explains a broad spectrum of observed surging behaviour in a single framework, and offers an answer to the wider question of why the majority of glaciers do not surge.

Environmental sciences, Meteorology. Climatology

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